Journal
BIOSENSORS & BIOELECTRONICS
Volume 26, Issue 7, Pages 3254-3259Publisher
ELSEVIER ADVANCED TECHNOLOGY
DOI: 10.1016/j.bios.2010.12.036
Keywords
Ochratoxin A; Aptamer; Electrochemical biosensor; Screen printed; Mycotoxins
Categories
Funding
- Aragon Government (Science, Technology and University Department)
- ACP Co. (Aragonesa de Componentes Pasivos SA, Tarazona, Spain)
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Ochratoxin A (OTA) is one of the most important mycotoxin contaminants of foods, particularly cereals and cereal products, with strict low regulatory levels (of ppb) in many countries worldwide. An electrochemical competitive aptamer-based biosensor for OTA is described. Paramagnetic microparticle beads (MBs) were functionalized with an aptamer specific to OTA, and were allowed to compete with a solution of the mycotoxin conjugated to the enzyme horseradish peroxidase (OTA-HRP) and free OTA. After separation and washing steps helped with magnetic separations, the modified MBs were localized on disposable screen-printed carbon electrodes (SPCEs) under a magnetic field, and the product of the enzymatic reaction with the substrate was detected with differential-pulse voltammetry. In addition to magnetic separation assays, other competitive schemes (direct/indirect aptasensors performed on the SPCEs surface or using gold nanoparticles functionalized with the aptamer) were preliminary tested, optimized and compared. The magnetic aptasensor showed a linear response to OTA in the range 0.78-8.74 ng mL(-1) and a limit of detection of 0.07 +/- 0.01 ng mL(-1), and was accurately applied to extracts of certified and spiked wheat samples with an RSD lower than about 8%. (C) 2010 Elsevier B.V. All rights reserved.
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